A mutation is a change in a gene that can be inherited if it occurs in a sex cell. Mutations can have positive, negative, or neutral effects. There are several types of mutations, including deletions, inversions, translocations, and point mutations such as substitutions, deletions, and insertions. Genetic screening through tests such as amniocentesis and chorionic villi sampling can detect over 200 genetic disorders in fetuses. Genetic counseling informs individuals about genetic disorders that may affect their offspring.

2.  A mutation is a change in a gene
 A mutation can only be inherited in it
occurs in a sex cell
 Effects of mutations can be:
› Positive
› Negative
› Neutral

3.  Deletion – loss of a
piece of a
chromosome

4.  Inversion – piece of
a chromosome
breaks off, flips
around, and
reattaches

5.  Translocation – a
piece of one
chromosome breaks
off and reattaches
to a nonhomologous
chromosome

6.  Nondisjunction – chromosome fails to
separate from its homologue during
meiosis

7.  Point Mutation – one nucleotide is
changed in the DNA sequence
› Substitution
› Deletion
› Insertion

8.  Substitution – one
nucleotide replaces
another

9.  Deletion – one or
more nucleotides
are deleted

10.  Insertion – one or
more nucleotides
are added to a
gene

11.  Deletion and insertion mutations can
both result in frameshift mutations, where
all amino acids downstream change

12.  Genetic screening – examination of a
person’s genetic makeup
› Karyotypes, tests for proteins, DNA tests
 More than 200 genetic disorders can
now be detected in the fetus

13.  Amniocentesis –
removal of amniotic
fluid from around the
fetus between the
14th and 16th week of
pregnancy

14.  Chorionic villi
sampling - A sample
from the zygote
between the 8th and
10th week of
pregnancy

15.  Genetic counseling – the process of
informing a person or couple about their
genetic makeup
› Informs individuals about problems that
might affect their offspring
› Predicts the likelihood that a couple will
produce an affected child

16.  Treat the symptoms
 Prevent symptoms

17.  Gene therapy – technique that places a
healthy copy of a gene into the cells of
a person whose copy of the gene is
defective